I've written previously that the average brain volume of both Neanderthals (1650cc as approximately determined by measurement of cranial capacity) and Denisovans (as determined by associated high technology artefactual, abstract artistic as well as fossil bone size evidence) is larger than the average brain volume of modern Homo sapiens sapiens (1450cc). But does brain size really have any influence on intelligence? According to neuroscientists, it does.
"Researchers have been able to identify correlates of intelligence within the brain and its functioning. These include overall brain volume, grey matter volume, white matter volume, white matter integrity, cortical thickness and neural efficiency. Although the evidence base for our understanding of the neural basis of human intelligence has increased greatly over the past 30 years, even more research is needed to fully understand it." I support funding that research. [Source, Neuroscience and Intelligence, scientific research papers referenced below]
The Facebook (FB) video show Why Are Our Brains Different In Size? (click on link to view video) by Hashem Al-Ghaili of Your Amazing Body is a cute example of humorously politicized science. Al-Ghaili prefaces his FB posting of the video with the statement: "Bigger brain does not equal smarter human. Here is why." He further states in the opening of the video, "We all know someone who has a big head. Don't you think it's about time to bring them back down to earth?" This latter statement surely sounds like Al-Ghaili is trying to elicit emotion-driven reactional agreement over reason-based rational thinking. Even so, though the video moves quickly over and downplays it, he is forced to admit that at least some (maybe 10% according one scientific study that he conveniently fails to credit reference) of human intelligence is influenced by brain size.
He is clearly being disingenuous, intentionally simplistic and deliberately misleading with the snark. The snark is also clearly playing on envy. In the end, the video supports rather than negates the positive correlation between brain size and intelligence. He doesn't believe his own opening snarky comments negating the link. He's being provocative, drawing people in to find out otherwise about the impact of brain size on intelligence (and, with a snarky comment regarding Neanderthals, to thoughtfully question why some human species could go extinct - like due to overwhelming demographic mass migration, for example). Clever.
- Luders, E.; Narr, K. L.; Thompson, P. M.; Toga, A. W. (2009). "Neuroanatomical correlates of intelligence". Intelligence. 37 (2): 156–163. doi:10.1016/j.intell.2008.07.002. PMC 2770698 . PMID 20160919.
- Pietschnig J, Penke L, Wicherts JM, Zeiler M, Voracek M (2015). "Meta-analysis of associations between human brain volume and intelligence differences: How strong are they and what do they mean?". Neuroscience & Biobehavioral Reviews. 57: 411–32. doi:10.1016/j.neubiorev.2015.09.017. PMID 26449760.
- Narr, K. L.; Woods, R. P.; Thompson, P. M.; Szeszko, P.; Robinson, D.; Dimtcheva, T.; Bilder, R. M. (2007). "Relationships between IQ and regional cortical gray matter thickness in healthy adults". Cerebral Cortex. 17 (9): 2163–2171. doi:10.1093/cercor/bhl125. PMID 17118969.
- Gur, R. C.; Turetsky, B. I.; Matsui, M.; Yan, M.; Bilker, W.; Hughett, P.; Gur, R. E. (1999). "Sex differences in brain gray and white matter in healthy young adults: correlations with cognitive performance". Journal of Neuroscience. 19 (10): 4065–4072.
- Penke, L.; Maniega, S. M.; Bastin, M. E.; Hernandez, M. V.; Murray, C.; Royle, N. A.; Deary, I. J. (2012). "Brain white matter tract integrity as a neural foundation for general intelligence". Molecular Psychiatry. 17 (10): 1026–1030. doi:10.1038/mp.2012.66. PMID 22614288.
- Haier, R. J.; Siegel, B. V.; Nuechterlein, K. H.; Hazlett, E.; Wu, J. C.; Paek, J.; Buchsbaum, M. S. (1988). "Cortical glucose metabolic rate correlates of abstract reasoning and attention studied with positron emission tomography". Intelligence. 12 (2): 199–217. doi:10.1016/0160-2896(88)90016-5.